The term xe2x80x9cresectoscopexe2x80x9d used herein denotes endoscopic instruments wherein an optics and an electrode support fitted with a distal electrode are configured in a stem tube; and wherein the electrode support has the electrode supported therein in an axially displaceable manner and affixed by its proximal end to a slide block of the resectoscope; and wherein the slide block is manually displaceable in the axial direction when a grip is actuated in order to axially displace the electrode. Resectoscopes of the aforementioned kind are intended foremost for prostate resection but, depending on the particular design, may also be used for other surgical applications.
In prostate resection, the resectoscope is advanced by means of the distal end of the stem tube through the urethra into the inside of the prostate. When the electrode is loaded with high frequency (hf) current, it can be advanced and retracted by manually displacing the slide block, to which the electrode is proximally affixed, for the purpose of cutting tissue. In general, the electrode assumes the shape of a wire loop to resect tissue snippets. However, the electrode also may assume other geometries. For instance, the electrode may be shaped as a button electrode, a roller electrode, a knife electrode or the like, in order to be used for different applications such as coagulation, cutting and the like.
Problems are encountered in this regard in setting up the proper electric contact between the conductor wire applying a current to the electrode and its contact zone in the slide block. The electric contact at the slide block must be set up to an extension cable running to a separate hf generator.
In older designs, electrical contact was set up by means of a clamping screw and simultaneously mechanical affixation of the electrode support was reliably assured in the slide block. However, once the contact site charred, the entire slide block required replacement.
A design of that kind is known from FIG. 3 of both U.S. Pat. Nos. 4,917,621 and 4,919,131. Therein the slide block is fitted with a continuous clearance receiving the plug of the extension cable that makes electrical contact with the electrode support""s contact zone, which is freely accessible in the clearance. A clamping element acting on an affixation zone of the electrode support is configured distally from the clearance.
This design offers the advantage of separately mechanically affixing the electrode support and the clamping element on the slide block, as a result of which it is possible to first check the slid block""s appropriate mechanical operation. Thereupon, contact may be implemented with the plug. If the contact site should char, only the electrode support and the cable holding the plug would need to be changed. The clamping element and the slide block remain intact because the clamping element is separate.
This design of the known species however incurs the drawback of a rigorous plug guidance within the clearance, entailing a predetermined location on the cable issuing from the plug. This feature is a drawback as regards resectoscopes that, during surgery, for instance in the prostate, must be continuously rotated in order to have the electrode cut at different angles. This desideratum is impeded by the fixed angular position of the hf cable.
It is an object of the invention to create a resectoscope having improved properties regarding the exit of the hf cable.
In accordance with the present invention, the contact element comprises a clearance that makes the seating fully accessible at three sides. The electrode support received in the seating therefore is freely accessible at a circumferential angle of at least 180xc2x0 from all sides. The plug is designed to be a clamping plug, which is intrinsically retentive and pivotably engages the electrical contact zone of the electrode support and may be pivoted by a substantially large angle up to 180xc2x0 and even more about the axis of the electrode support. In the process, when the resectoscope is rotated, the cable suspended from the plug may be hanging from it in swiveling manner, leaving the rotation unhampered.
In further accordance with the present invention, the reliability of clamping of the clamping plug is improved because a groove formed therein assures reliable retention on the electrode support against detachment.